Handling Of Registration Reject In Mobile Communications

1. A method implementable by a user equipment (UE), comprising: transmitting a first request to a first network element of a first type of wireless network; receiving a first reject without integrity protection from the first network element; determining whether a number of times of receiving the first reject without integrity protection from the first network element exceeds a threshold number; and responsive to a determination that the number of times exceeds the threshold number, performing operations comprising: barring the first network element in response to receiving the first reject without integrity protection from the first network element; and transmitting a second request to a second network element of the first type of wireless network, wherein, in an event that a second reject is received from the second network element, the UE performs operations comprising: determining whether a cause number of the first reject and a cause number of the second reject are the same; and responsive to a determination that the cause number of the first reject and the cause number of the second reject are the same, performing either or both of: determining that a Subscriber Identify Module (SIM) card used in communications with the first network element and the second network element is invalid; and entering an operational mode in which no calls other than emergency calls can be made.

2. The method of claim 1 , further comprising: receiving the second reject from the second network element; and switching to communications with a second type of wireless network in response to receiving the first and the second rejects.

3. The method of claim 1 , further comprising: receiving an acceptance indication from the second network element; and storing an identification associated with the first network element such that first network element is not selected again when attempting to establish communications with the first type of wireless network again.

4. The method of claim 3 , wherein the first network element comprises a first Evolved Node B (eNodeB), a first Node B or a first Base Transceiver Station (BTS) of a first Public Land Mobile Network (PLMN), and wherein the second network element comprises a second eNodeB, a second Node B or a second BTS of the first PLMN.

5. The method of claim 1 , wherein the first request comprises a first tracking area update (TAU) request, a first routing area update (RAU) request, a first service request or a first location update request, wherein the first reject comprises a first TAU reject, a first RAU reject, a first service reject or a first location update reject without integrity protection received, wherein the second request comprises a second TAU request, a second RAU request, a second service request or a second location update request, and wherein the second reject comprises a second TAU reject, a second RAU reject, a second service reject or a second location update reject without integrity protection.

6. A method implementable by a user equipment (UE), comprising: transmitting a first request to a first network element of a first type of wireless network; receiving a first reject without integrity protection from the first network element; determining whether a number of times of receiving the first reject without integrity protection from the first network element exceeds a threshold number; and responsive to a determination that the number of times exceeds the threshold number, performing operations comprising: barring the first network element for a period of barring time in response to receiving the first reject without integrity protection from the first network element; and transmitting a second request to a second network element of the first type of wireless network after the period of barring time, wherein, in an event that a second reject is received from the second network element, the UE performs operations comprising: determining whether a cause number of the first reject and a cause number of the second reject are the same; and responsive to a determination that the cause number of the first reject and the cause number of the second reject are the same, performing either or both of: determining that a Subscriber Identify Module (SIM) card used in communications with the first network element and the second network element is invalid; and entering an operational mode in which no calls other than emergency calls can be made.

7. The method of claim 6 , further comprising: receiving the second reject from the first network element; and switching to communications with a second type of wireless network in response to receiving the second rejects.

8. The method of claim 6 , further comprising: receiving a second reject from the first network element; and storing an identification associated with the first network element.

9. The method of claim 8 , wherein the first network element comprises an Evolved Node B (eNodeB), a Node B or a Base Transceiver Station (BTS), and wherein the identification associated with the first network element comprises an identification of a cell associated with the first network element, an identification of a Public Land Mobile Network (PLMN) associated with the first network element, or a combination thereof.

10. The method of claim 8 , further comprising performing one of a number of operations, the operations comprising: refraining from attempting to establish communications with the first type of wireless network; and waiting for a period of wait time before attempting to establish communications with the first type of wireless network.

11. The method of claim 6 , wherein the first request comprises a first tracking area update (TAU) request, a first routing area update (RAU) request, a first service request or a first location update request, wherein the first reject comprises a first TAU reject, a first RAU reject, a first service reject or a first location update reject without integrity protection, and wherein the second request comprises a second TAU request, a second RAU request, a second service request or a second location update request.

12. A method implementable by a user equipment (UE), comprising: transmitting a first request to a first network element of a first wireless network; receiving a first reject without integrity protection from the first network element; counting a number of times of receiving the first reject without integrity protection from the first network element; determining whether the number of times of receiving the first reject without integrity protection from the first network element exceeds a threshold number; and responsive to a determination that the number of times exceeds the threshold number, performing operations comprising: barring a tracking area, a routing area or a location area associated with the first network element or the first wireless network in response to receiving the first reject without integrity protection from the first network element; starting a back-off timer; and transmitting a second request to a second network element of a second wireless network either immediately or after the period of barring time, wherein, in an event that a second reject is received from the second network element, the UE performs operations comprising: determining whether a cause number of the first reject and a cause number of the second reject are the same; and responsive to a determination that the cause number of the first reject and the cause number of the second reject are the same, performing either or both of: determining that a Subscriber Identify Module (SIM) card used in communications with the first network element and the second network element is invalid; and entering an operational mode in which no calls other than emergency calls can be made.

13. The method of claim 12 , further comprising: receiving the second reject from the second network element; stopping the back-off timer; and performing one or more operations pertaining to a situation in which the SIM card is invalid.

14. The method of claim 13 , wherein the first network element comprises a first Evolved Node B (eNodeB) of a first Public Land Mobile Network (PLMN), and wherein the second network element comprises a second eNodeB of a second PLMN.

15. The method of claim 12 , further comprising: receiving the second reject from the second network element; stopping the back-off timer; and performing one or more operations pertaining to a situation in which the SIM card is valid and is denied of services from at least the first wireless network and the second wireless network.